Disk drives are a type of information storage device that store information on at least one spinning disk. Other types of information storage devices include, for example, magnetic tape drives which retrieve stored information on magnetic tape (e.g. linear tape drive, helical scan tape drive). There are several types of disk drives. Magnetic hard disk drives typically store information on non-removable rigid magnetic disks. There are also optical disk drives, which typically retrieve information stored on removable optical disk media. Also for example, there are magneto-optical disk drives, which share some of the characteristics of optical disk drives and magnetic hard disk drives.
All types of disk drives typically include a spindle motor that supports and spins at least one annular disk media. Although past disk drive spindle motors utilized ball bearings, ball bearings have been replaced by fluid bearings in many contemporary disk drive spindle motors, for example to reduce non-repeatable runout, vibration, and/or acoustic noise.
The annular disk media is typically fitted over a rotatable disk mounting hub of the spindle, and clamped to the disk mounting hub by a disk clamp that is positioned at the top of the disk mounting hub and forced downward by the action of one or more fasteners. In most disk drive applications, the disk clamp is fastened by a plurality of fasteners that screw into the top of the disk mounting hub. However, in some disk drive applications, the disk clamp may be fastened by one central fastener that screws into a rotating spindle shaft. In such applications, the disk mounting hub is typically press-fit onto the rotating spindle shaft, and may also be bonded thereto. The press-fit interface may be subjected to stresses caused by the clamping force, and the press-fit assembly process may undesirably cause local plastic deformation of the hub.
A disk drive, especially one that is installed in a mobile device such as a laptop computer, is often subjected to mechanical shocks and sharp accelerations from impacts during non-operation. Such mechanical shocks and accelerations can further stress the disk clamp, and may even overcome the press-fit and bond that fixes a disk mounting hub to the rotating spindle shaft, causing undesirable slippage and/or spindle oil leak and contamination through the press-fit interface. The risk of such problems may be exacerbated by operating or non-operating temperature at or near the extremes of the disk drive's expected temperature range.
Therefore, there is a need in the art for an improved disk drive spindle design in which the press-fit interface and/or bond between a disk mounting hub and a rotating shaft has a bond strength that is better able to resist disk clamping loads and mechanical shocks throughout the expected operating and non-operating temperature range. There is also a need in the art for an improved disk drive spindle design that reduces the risk that the press-fit interface and/or bond between a disk mounting hub and a rotating shaft might allow an unacceptable amount of oil leakage from within the spindle. There is also a need in the art for an improved disk drive spindle design that can be mass-manufactured at acceptably low cost, and in which plastic deformation of the hub is reduced or eliminated during assembly.